1. Field of the Invention
The present invention relates to a structure for connecting a shield layer of a terminal of a shielded cable to a shield wall.
2. Description of the Related Art
Hitherto, there has been known such a kind of a terminal connecting structure illustrated in FIG. 6. In this structure, a stepped connecting tube 3 having a front-end side portion reduced in diameter is press-fitted into and fixed in a mounting hole 2 opening in a longitudinally extending shield wall 1. An end portion of a shield layer 5, constituted by a braided wire, is exposed at a terminal of a shielded cable 4. Then, the exposed portion is turned up and put upon a corresponding end portion of the outer sheath 7 through an underlay C-ring 6. The turned-up portion 5A of the shield layer 5 is inserted into a diameter reduction portion 3A of the connecting tube 3 and fastened thereto by caulking the diameter reduction portion 3A so that the shield layer 5 is sandwiched between the portion 3A and the C-ring 6.
However, the diameter reduction portion 3A of the connecting tube 3 is caulked along its entire length in the related art, a portion 8 between the diameter reduction portion 3A and a diameter enlargement portion 3B of the connecting tube 3 is formed like a bellmouth, whose diameter gradually increases from portion 3A to portion 3B at a place corresponding to a side of the turned-up end portion of the shield layer 5 (at the right end side, as viewed in FIG. 6), and the portion 8 is merely engaged to the shielded cable 4. Thus, when the shielded cable 4 is pushed forward (that is, to the left, as viewed in this figure), the above engaging portion 8 becomes an engaging point so that engaging forth can be obtained. Whereas, when the shielded cable 4 is pulled backwardly, the engaging force is weak so that the shielded cable 4 easily comes off from the connecting tube 3.
Further, in the related art, the front end of the connecting tube 3 is set at the same position as a position of a folded-back portion 5A of the shield layer 5, or at a position behind the folded-back portion 5A. Consequently, the folded-back portion 5A of the shield layer 5 is exposed. Thus, there are fears that the portion 5A may touch other components and may be damaged, and that when the connecting tube 3 is caulked, the shield layer 5 may be cut by the front edge of the tube 3.
The invention is accomplished in view of the aforementioned circumstances. Accordingly, an object of the invention is to increase a fastening force to connect the shield layer to the shield wall. Further, another object of the invention is to protect the exposed portion of the shield layer.
To achieve the foregoing objects, according to a first aspect of the invention, there is provided a structure for connecting a terminal of a shielded cable comprising:
a shielded cable having a shield layer exposed at the end of the shielded cable; and
a connecting tube attached to an opening formed in a shield wall,
wherein the connecting tube has a large diameter portion at each end and a small diameter portion; and
the small diameter portion is caulked to be press-fitted to the shielded cable.
According to a second aspect of the invention, there is provided the structure according to the first aspect of the invention, wherein the connecting tube has two intermediate portions, whose diameters taper from a large diameter to a small diameter.
According to a third aspect of the invention, there is provided the structure according to the first or second aspect of the invention, wherein the end of the connecting tube covers the exposed shield layer.
According to a fourth aspect of the invention, there is provided the structure according to any one of the first to third aspects of the invention, wherein one of the large diameter portions is larger in diameter than the other thereof.
According to a fifth aspect of the invention, there is provided the structure according to any one of the first to fourth aspects of the invention, wherein one of the large diameter portions has a guiding tapered portion, which is bent inwardly, at the end of the large diameter portion.
According to a sixth aspect of the invention, there is provided a structure for connecting a terminal of a shielded cable comprising:
a shielded cable having a shield layer exposed at the end of the shielded cable; and
a connecting tube attached to an opening formed in a shield wall,
wherein the end of the connecting tube covers the exposed shielded cable; and
the connecting tube is caulked to be press-fitted to the shielded cable.
According to a seventh aspect of the invention, there is provided the structure according to the sixth aspect of the invention, wherein the end of the connecting tube is bent inwardly to cover with the exposed shielded cable.
According to the first aspect of the invention, the connecting tube is caulked in such a manner as to form the two bellmouths so that the radial dimensions of the bellmouths gradually increase in opposite directions, respectively. Thus, in the case of moving the shielded cable in both the forward and backward directions, the bellmouths serve as an engaging point for holding the shielded cable and thus can restrict the movement of the shielded cable. Consequently, the fastening force can be increased.
According to the fourth aspect of the invention, the diameter at the front end side of the connecting tube is made to be small. This facilitates an operation of inserting the connecting tube into the shielded wall.
According to the fifth aspect of the invention, the guiding tapered part leads the connecting tube into the mounting hole. Consequently, the operation of inserting the connecting tube into the mounting hole is facilitated.
According to the third or sixth aspect of the invention, the front end portion of the connecting tube covers and protects the front end of the shield layer and the vicinity thereof, thereby preventing the front end of the shield layer from touching other components. Moreover, the shield layer is prevented from being cut by the edge of the front end portion of the connecting tube when the connecting tube is caulked.
According to the seventh aspect of the invention, the front surface of the front end portion of the shield layer is covered, so that the front end portion thereof is more reliably protected.